For a low end Brother, i'd go buy a new one (if I couldn't fix it myself) before taking it to a repair shop.
Shops in my area charge $100 for basic servicing and cleaning. That doesn't include any part repair! CS6000i is $140 on Amazon. You can get even cheaper ones than that.
For my high end machine, I go and get a service when the light comes on (apparently it's 3 million stitches? They say to do annual, but I trust the light, since it knows how often it is being used. For me that is about 1 3/4 years.)- but when the cost of service is 50% (or even 100%) of a new machine, no way.
But before you do anything- clean, oil, change needle, rethread. That solves a lot of problems.